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Julia Tasset
Laura Hildreth
Exploring Biomedical Research
10 March 2011
Investigational Report
Dr. Jose A. Cancelas is not from the United States. This fact is evident from the
first moment that one reads the nameplate on his office door and strikingly obvious when
he opens his mouth to make an introduction. Born, raised and educated in Spain, he
earned his undergraduate, MD and PhD degrees in Madrid. Operating within the
Division of Experimental Hematology and Cancer Biology, he splits his time between a
research lab at Cincinnati Children’s Hospital Medical Center (CCHMC) and Hoxworth
Blood Center, where is he also has an appointment as the Director of Research.
First, I wish to elucidate my motivations for pursuing a research position in a
hematology/oncology lab, such as Dr. Cancelas’s. During the summer before my
freshman year of college, I was selected to participate in a clinical shadowing program,
CCHMC’s High School Summer Internship. I was paired with a MD mentor in the
Department of Oncology who managed patients primarily affected by leukemia
(overwhelming the most common childhood cancer). Not only through my mentor, but
also through the other attendings, medical students, residents, and nurses, I learned so
much about the biological origins of the disease, the metabolic pathways of pediatric
cancer, its genetic footprint, and the social and familial impacts such a diagnosis may
bring. I was emotionally touched by these patients and families (many of whom had
flown around the world for treatment at CCHMC) and also impressed by how much is
still unknown about the disease. Understanding how cancer comes about and how to
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most effectively treat it is still startling unclear, given all the advances of modern
medicine in this day and age. I therefore am interested in working in this field for the
aforementioned personal and scientific reasons, stemming from my experience at
CCHMC last summer.
The Stem Cell Biology program is a subdivision within the Basic Research
section (whose stated goal is to develop novel therapies that may have clinical
applications in the future) of the Division of Experimental Hematology and Cancer
Biology. Dr. Cancelas’s falls into the Stem Cell Biology program since his area of
investigation looks at the origins of how hematopoietic stem cells (HSC) and blood
progenitor cells proliferate and/or differentiate normally or abnormally.
However, within the Basic Research section of the Division of Experimental
Hematology and Cancer Biology, there exists other programs distinct from that of Dr.
Cancelas. The Hematology and Gene Therapy program directs its time into examining
possible genetic therapies to eliminate genetic disease and genetic cancers (like the BCRABL leukemia gene and the BRAC breast cancer gene). The Hematological Malignancy
program looks at the metabolic and cellular pathways involved in the development of
leukemia, myelodysplasia, and myeloproliferative disease. The Signaling and Drug
Discovery program examines signaling mechanisms which regulate the formation of new
blood cells, tumors, and metastasis. And finally, the Cancer Biology and Neural Tumors
program attempts to discern the what factors are turned off when tumors form so as to
better defend against tumorgenesis. This vast array of programs and focuses of research
are just as prolific within Experimental Hematology and Cancer Biology’s other research
sections (Translational Research and Clinical Research). This underscores how much
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activity is going on in this field and how much still has yet to understood regarding this
devastating disease.
Dr. Cancelas explained that hematology and oncology are two interrelated fields
that can be distinct at times. Blood cancers (leukemias and lymphomas) are the main
disorder which connects the two fields. Dr. Cancelas considers himself to be a
hematologist, even though he works within a divided department. Therefore, his work
primarily examines the bone marrow, where these cells are made. HSC have the ability
to divide into new HSC, or differentiate into any of the components which make up
normal blood. From his website, Dr. Cancelas’ lab specifically focuses on, “the
molecular determinants that regulate the proliferation, survival, homing and retention of
hematopoietic stem cells in relation with the so-called “stem cell niche” in benign and
malignant hematopoietic” [1]. This includes cell surface signaling proteins and gap
junction communication proteins, like connexin 43 (Cx43).
Gap junctions allow the transmission of small molecular signals (chemical or
electrical) between neighboring cells. They are composed of six connexin tubes arranged
in a circle. Each neighboring cell contributes one hemichannel to the gap junction, whose
permeability depends on the type of connexins which make it up (connexins are named
for their molecular weight). (For an illustration of this set up, please see Figure 1A&B
below.) It has been proved that Cx43 is expressed with some frequency in the cells of
bone marrow and HSC.
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Based on scientific and hematological journal publications, it has been established
that Cx43 is expressed by the BM and upregulated upon stress [2,4,7]. Also, loss of
function of Cx43 in the hematopoietic microenvironment induces long-term bone
marrow failure and delayed hematopoietic response to myeloablative stress due to a
deficient hematopoietic microenvironment [6]. Additionally, preliminary results from
another source demonstrate the presence of Cx43-dependent GJ between stroma and
leukemia cells in BM biopsies of AML patients [5].
Therefore, it can generally be said that the role of Cx43 in leukemogenesis has not
been well characterized. This is why I wish to study this promising new area of
investigation. It is now hypothesized that the closing or elimination of Cx43 gap
junctions may contribute to the containment of leukemia disease, since cells would not
be able to communicate and spread messages which induce leukemia development in
healthy HSC.
This can be tested both in vitro and in vivo by employing BCR-ABL gene to
induce leukemia in groups of mouse subjects which selectively have knocked out the
gene which codes for Cx43 (via the Cre recombinase enzyme and the flox method). In
the grand scheme, this project will form part of a larger project that intends to explore
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the dependence of Cx43 expression in leukemic hematopoiesis. The long-term goal of
this project is to determine whether Cx43 GJ may be a relevant therapeutic target to
eradicate leukemic stem cells.
The Summer Undergraduate Research Fellowship (SURF) program at CCHMC,
and Dr. Cancelas in particular, allowed me to pursue such an ambitious project. Being
a first year biology student, I had neither the contacts nor the technical expertise to
bring this project to fruition without major guidance.
This past winter, I simply knew that the SURF program existed, that I wanted to
work in hematology/oncology, and began to email primary investigators who were
listed as operating a lab in these departments. Dr. Cancelas was kind enough to not
only respond and offer me a chance to be the SURF intern in his lab, but also the
opportunity to tailor my own project and apply for grant funding for the project. I
received plentiful help and coaching from Dr. Cancelas, including but not limited to,
selecting of scientific journals to study, selection of an appropriate grant through the
American Society of Hematology, and suggestions of countless revisions to the
writing of my grant proposal.
This summer, I will be able to work on the project in a supervised, yet somewhat
independent fashion. Hopefully, the tutorage of other lab staff and post doctoral
fellows will aid in my first ever transition to a practical lab setting. This project was
(and will be) an incredible amount of work, but I will never forget how Dr. Cancelas
gave me the chance to strive and prove myself by working hard and learning a lot.
This will serve as a model for my future when I am, hopefully someday, in his shoes,
working as the head of a research facility and a student knocks on my door looking for
the opportunity to learn about science, and disease.
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Works Cited
1. “Cancelas Laboratory Research Interests.” Cancelas Lab. Cincinnati Children’s. 02
Mar 2011. Web. <http://www.cincinnatichildrens.org/research/div/exphematology/labs/stem/cancelas/default.htm
2. Montecino-Rodriguez E, Dorshkind K: Regulation of hematopoiesis by gap junctionmediated intercellular communication. J Leukocyte Bio 70:341,2001.
4. Cancelas JA, Koevoet WLM, de Koning AE, Mayen AEM, Rombouts EJC,
Ploemacher RE: Connexin-43 gap junctions are involved in multiconnexin-expresssing
stromal support of hemopoietic progenitors and stem cells. Blood 96:498,2000.
5. Krenacs T, Rosendaal M: Connexin 43 gap junctions in normal, regerating, and
cultured mouse bone marrow and in human leukemias: their possible involvement in
blood formation. Am J Pathol 152:993,1998.
6. Preley CA, Lee AW, Kastl B, Igbinosa I, Yamada Y, Fishman G, Gutstein DE,
Cancelas JA: Bone marrow connexin-43 expression is critical for hematopoietic
regeneration after chemotherapy. Cell Comm and Adhesion 12:307,2005.
7. Rosendaal M, Green CF, Rahman A, Morgan D: Up-regulation of connexin43+ gap
junction network in haemopoietic tissue before the growth of stem cells. J Cell Sci
107:29,1994.